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A fast-dynamic unipolar switching control scheme for single-phase inverters in DC microgrids

: Pokharel, M.; Hildebrandt, N.; Ho, C.N.; He, Y.


IEEE transactions on power electronics 34 (2019), Nr.1, S.916-927
ISSN: 0885-8993
Fraunhofer ISE ()

This paper presents the digital implementation of a boundary controller with unipolar switching characteristic for single phase voltage source full bridge inverters. This paper expands the application of second order switching surface based control method to unipolar switching of single phase voltage source inverters (VSI) using finite-state machine. The finite state machine has been formulated considering four different states of the inverter; Positive, Zero1, Negative and Zero2. The second order boundary control governs current state of the system and provides proper switching action to keep the system within desired reference. The control law is implemented digitally in F28m35x digital control card. A full bridge inverter topology is used to achieve the three-level voltage switching. Various simulations and experiments were performed in a 550VA, 120V, 60Hz VSI with digitally implemented controller to verify the theoretical predictions. A high-quality voltage output was obtained for various loading conditions. The transient performance of the controller was investigated using a reference and load changes. A comparison of the implementation was made with the exiting classical controllers to verify the fast-dynamic response of the system.